Andy, a Negator with the ability "Undead," has been long in search for someone with the ability to give him a 'real death.' Fuko Izumo brings misfortune to those around her due to her ability "Unluck." The two decide to join the Union, an organization which aims to control and protect the world from unidentified phenomena. The two uncover the mystery of the world as they search for the "greatest death ever."